10900K and 10900 are in "avoid territory" as expected. 10700K is a slightly cheaper 9900K tied to a newer motherboard platform which at least one more CPU upgrade available to it. If you really need to go Intel and haven't got a Coffee Lake system yet. Look no further then 10700K (cheaper 9900K) or opt for 10600K (cheaper 8700K). The extra two cores do little to nothing for 10900K since you end-up becoming thermally limited (ends-up falling behind 3900X instead of contesting it). Honestly, Intel could have done a simple price war on their existing Coffee Lake SKUs and just waited until they moved beyond Skylake-derivatives. They would have saved on R&D and validation costs.
Gigabyte Z390 AORUS-PRO Coffee Lake R 9700K, 2x16GiB of G.Skill RIPSAW DDR4-3600, Sapphire RX 6900XT, Seasonic GX-850 and Fractal Define 7 (W)
Ivy Bridge 3570K, 2x4GiB of G.Skill RIPSAW DDR3-1600, Gigabyte Z77X-UD3H, Corsair CX-750M V2, and PC-7B